Add missing consts

[DanielVandH]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.47%. Comparing base (f9fd686) to head (846a907).
Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #238      +/-   ##
==========================================
+ Coverage   90.00%   90.47%   +0.47%     
==========================================
  Files          11       11              
  Lines        1900     1901       +1     
==========================================
+ Hits         1710     1720      +10     
+ Misses        190      181       -9     

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[jishnub]

My understanding was that parametric types are assumed to be consts by default, and don't need to be annotated.

[DanielVandH]

I think there there's a difference, e.g.

julia> module Test
       T = Union{Int, Real}
       f(x) = x isa T ? 2.0 : 1
       end
Main.Test

julia> module Test2
       const T = Union{Int, Real}
       f(x) = x isa T ? 2.0 : 1
       end
Main.Test2

julia> @code_warntype Test.f(2.0)
MethodInstance for Main.Test.f(::Float64)
  from f(x) @ Main.Test REPL[1]:3
Arguments
  #self#::Core.Const(Main.Test.f)
  x::Float64
Body::Union{Float64, Int64}
1 ─ %1 = (x isa Main.Test.T)::Bool
└──      goto #3 if not %1
2 ─      return 2.0
3 ─      return 1


julia> @code_warntype Test2.f(2.0)
MethodInstance for Main.Test2.f(::Float64)
  from f(x) @ Main.Test2 REPL[2]:3
Arguments
  #self#::Core.Const(Main.Test2.f)
  x::Float64
Body::Float64
1 ─ %1 = (x isa Main.Test2.T)::Core.Const(true)
└──      goto #3 if not %1
2 ─      return 2.0
3 ─      Core.Const(:(return 1))

[jishnub]

I meant the const annotation is unnecessary in case the global variable is a parametric type alias (as in the change in this PR):

julia> module Test
       struct A{T} x::T end
       C{T} = A{T}
       f(x) = x isa C{Int} ? 1 : 2.0
       end
Main.Test

julia> module Test2
       struct A{T} x::T end
       const C{T} = A{T}
       f(x) = x isa C{Int} ? 1 : 2.0
       end
Main.Test2

julia> @code_typed Test.f(Test.A(2.0))
CodeInfo(
1 ─     nothing::Nothing
└──     return 2.0
) => Float64

julia> @code_typed Test2.f(Test2.A(2.0))
CodeInfo(
1 ─     nothing::Nothing
└──     return 2.0
) => Float64

This used to be necessary at one point, but not anymore on recent versions.

I am ok with the change either way, but I'm unsure if this helps with performance.

[DanielVandH]

Interesting, I didn't know about that. It's up to you then, I don't mind if this gets closed. It does have the nice benefit that it at least makes the types consistent with the rest of the types which have a const.

[dlfivefifty]

I think making it explicit is better